Invertebrate hydraulic microhabitat and community structure in Callitriche stagnalis Scop. patches

Abstract

In this paper, we report the structure of the benthic invertebrate community in submerged Callitriche stagnalis Scop. stands in relation to velocity, in a Scottish river, the Blane Water. We compared the community within the macrophyte beds to that of adjacent unvegetated substrate. Callitriche stagnalis stands supported different taxa richness (no. of taxa) and abundances (no. of individuals) of benthic invertebrates than the unvegetated riffle substrate (Wilcoxon Matched-Pairs test: p<0.01, n = 10). To see if different sections of the stands supported different invertebrate communities, samples were taken from the outer, mid and root sections of the stands. The sections were separated by Detrended Correspondence Analysis (DCA) using their macroinvertebrate communities (eigenvalues: axis 1 = 0.6, axis 2 = 0.136). Abundance and taxa richness were different between the outer and mid sections, and between outer and root sections (Wilcoxon Matched-Pairs test: respectively p<0.05, p<0.01, n = 10). Community structure also differed between sections. The outer section community had a structure similar to that of an extreme environment where Simuliidae were dominant. Ephemerella ignita dominated in the mid and root sections. Differing combinations of plant structure and velocity appear to be a major factor influencing habitat structure, creating a range of stability conditions in the stands, which support the observed diversity of invertebrate assemblages present.